This specification relates to transistors, such as VLSI (very-large-scale integration) for CMOS (complementary metaloxidesemiconductor) transistors. Switches and field-effect transistors that use nanoelectro-mechanical-system (NEMS) to address the thermodynamic limits of MOSFETs have been demonstrated. NEMS exploits the mechanical degree of freedom using movable component like gate or channel. Nanowires have also demonstrated extreme high performance as field effect transistors with near-ballistic transport.
A NEMS switch (a two terminal device) is a well-known MEMS device that utilizes pull-in/pull-out movement of suspended components. Previous studies of two terminal NEMS switches have shown abrupt on/off switching, and reduced subthreshold slope (SS), which is the steepest transition rate for turning off a transistor, with movable gate or channel using various materials like metal, carbon nanotube, silicon carbide, Si nanowire (NW), or graphene. Two terminal NEMS switches suffer from the fundamental design limitation that when turned on, the current relies solely on the contact resistance between the two contact surface and that a typically large threshold voltage is used to pull in the device. Therefore two terminal switches have no control over their on or off current and their performances depend heavily on in the nature of the mechanical contacts which is still not well understood.
Three terminal suspended gate NEMS field effect transistors are configured as a traditional transistor with a gate voltage used to independently tune the current from source to drain. However the large micrometer sized metal suspended gate electrode in previously reported devices have limited operational speed of several MHz due to the large mass of the moving components